The importance of brake testing!
Any service involves checking the brakes visually, but to really know HOW the vehicle would react in a brake EMERGENCY situation requires a different approach.
There are basically only 2 brake test machines available: a roller brake tester and a skid plate brake tester http://www.youtube.com/watch?v=tdrj4NrUsQA&feature=relmfu
There is also a decelometer, which is falsely classified as a brake tester, because only the roller and skid plate brake tester can measure the brake force on each wheel which is vital to determine the overall stopping performance of a motor vehicle.
As a fourth option you can use a high speed brake test, but this is a very dangerous test http://www.youtube.com/watch?v=cWBBnpwqsR0